Dear Matpower users, I have some questions about tap ratios in Matpwer.
What does it mean if the tap ratios TAP are set to 0? Tap ratio=0 is used to indicate that the branch is a non-transformer branch, while 1 indicates a transformer branch. Even if you set the tap ratio = 0 for a transformer, MATPOWER internally uses a unity tap ratio meaning a 1:1 voltage transformation. I have previously run some power flows without caring about the tap ratios (TAP = 0). Now I set them to 1, and got quite different results. I don’t think this should happen. With 0 or 1, the power flow results should be same. I can't see that the admittance matrix in Figure 3.1 in the manual is well defined for zero tap ratio, so I thought setting them to 0 was like deactivating them. Also, if I want to run an OPF with active tap changers, would it be best to include the tap ratios directly in the optimization constraints or to change the tap ratios in a callback function? Or maybe I can run several OPFs and change the tap ratios manually between each? Incorporating tap changers in OPF is a non-trivial task. Moreover, I don’t think there is a callback function in PF or OPF. Here are some relevant discussions from the mailing list. https://www.mail-archive.com/[email protected]/msg04162.html https://www.mail-archive.com/[email protected]/msg03339.html Note that there is a pending pull request for this feature. You can try that out if you like. Shri Regards, Elis Nycander
